1. Field of the Invention
The present invention relates to a signal processing apparatus such as a digital broadcasting receiver and a stream processing method used for the same.
2. Description of the Related Art
In recent years, a real-time transmission system for transmitting, in real time, a data stream such as a digitally compression-encoded audio/video signal has been developed. The real-time transmission system executes the transmission of the data stream by using a transport stream. The transport stream is constituted by transport stream packets.
Recently, a system for transmitting groups of packets with time information respectively added thereto has been developed. For example, a data transmitting device for transmitting signal data with a count value of a counter added thereto is disclosed by Jpn. Pat. Appln. KOKAI Publication No. 2000-341234.
In a digital broadcast such as a terrestrial digital broadcasting, broadcast program data is formed by the above-mentioned transport stream.
In the digital broadcasting receiver, a broadcast signal is received and demodulated by a tuner then the transport stream is extracted from the broadcast signal. The transport stream packets constituting the transport stream are transmitted to the decoder in the broadcasting receiver in real time to be decoded there. The decoder is usually designed so that its decoding speed is determined in accordance with the receiving timing of each packet. Since each of the packets is transmitted to the decoder in real time at the timing corresponding to reproduction timing, the decoder can normally decode and reproduce the transport stream.
In the meantime, recently, a home network system capable of connecting a plurality of electrical household appliances with one another has been needed to be realized. The digital broadcasting receiver for use in the home network system needs a function for decoding and reproducing not only the transport stream transmitted in real time like the broadcast program data but also a transport stream transferred at an arbitrary speed via a network from a storage medium.
However, the transport stream read out from the storage medium is transmitted to the digital broadcast receiver at a higher speed than the intrinsic transport rate of the transport stream. Therefore, if the digital broadcast receiver directly inputs the transport stream transmitted from the storage medium via the network into the decoder, a failure such as the reproduction of the transport stream at an abnormally higher speed is caused. Accordingly, it is required for the digital broadcasting receiver to execute particular decode control to switch the operation control method of the decoder in accordance with a kind (real-time stream/non real-time stream) of the stream to be decoded.
The digital broadcasting receiver for use in the home network system also needs a function of recording the transport stream received via the network in an external device such as, for example, an IEEE 1394 standardized digital video cassette recorder (VCR). In this case, the transport stream is needed to be transmitted in real time to the external device.